Hydropneumatic salvage system



Oct. 14, 1969 E. E. HORTON HYDROPNEUMATIC SALVAGE SYSTEM Filed June 20,1967 COMPRESSOR ACCUMULATOR I000 PSI lNVENTUI? EDWARD E HORTON US. Cl.114-52 9 Claims ABSTRACT OF THE DISCLOSURE A system and apparatus forretrieving objects from great water depths which includes a hollowvessel having grappling hooks mounted thereto and a pressure system forrendering the vessel positively buoyant by utilizing long columnar headsof water in combination with an air compressor having a relatively lowpressure capability.

This invention relates to an apparatus for raising sunken objects fromgreat depths and more particularly relates to an apparatus for raisingsuch objects by hydropneumatic means.

The present invention will carry out salvage operations at depthsheretofor believed impractical for meaningful results. As will beexplained, apparatus which embodies this invention can be used forlifting several thousand tons from depths of more than 20,000 feet.Heretofore, the use of air and gas at great depths has proved unfeasiblefor the reason that air compressors, which can satisfy the high airpressure requirements when working at such depths are not commerciallyavailable and gas generators for these pressures are dangerous becauseof the explosive nature of the gases which must be used. In order toovercome these problems and limitations, it is a primary object of theinvention to provide a salvagingapparatus for engaging and raisin asunken object at depths of several miles by means of a lifting vesselwhich is buoyed by pressures obtained through a two-phase fluid flow ofair and Water.

Another object of this invention is to provide a ship salvagingapparatus which can recover objects from great depths by the use of aircompressors and water pumps commercially available with output pressureson the order of 1,000 psi.

Another important object of the invention is to provide a hydropneumaticpumping means to pressurize a submerged lifting chamber to relativelyhigh pressures by using compressors having relatively low outputpressures.

Another important object of the invention is to provide an apparatus forpressurizing air by building up a columnar pressure head of alternatevolumes of air and water which acts downwardly to increasingly compresseach succedingly lower air volume.

A yet further object of the instant invention is to provide an apparatuswhich employs both a pipe string and an attached pressurized containerfor lifting sunken objects.

These and other objects of the invention will become more apparent tothose skilled in the art by reference to the following detaileddescription when viewed in light of the accompanying drawings, wherein:

FIGURE 1 show a diagrammatic perspective view of the invention with apipe string and hollow lifting vessel in place ready for raising asunken object;

FIGURE 2 is a detailed perspective partly in section of a hollow liftingchamber; and

FIGURE 3 is a diagrammatic-schematic view of the hydropneumatic pumpingsystem.

Referring now to the drawings, wherein like numerals indicate likeparts, a ship 10 is shown positioned over United States Patent M 3 ,472, l 9 l Patented Oct. 14, 1969 an object to be retrieved. A derrick ortower 12 is secured topside thereof and is of the type common to the oildrilling industry. Derricks of this type sequentially secure and combinea series of pipe sections 14 into a pipe string 16. The pipe sections 14are secured together, usually by mating threads, as is well known to theart. The joints between these pipe sections must be sufficiently tightto prevent leakage during submersion. Extending the length of the pipestring and secured to the outer wall of each pipe section, is anelectric control cable 17.

Rigidly secured to the bottom end of the pipe string at .25 is a liftingvessel 18. The electrical cable 17 extends from an electric power sourceand its controls on the deck to the vessel for accomplishing certainmovements of grappling devices hereinafter described. The vessel 18 issemi-cylindrical in configuration and includes parallel inner and outerwalls 20' and 22, end walls 24, and side walls 26. A chamber 27 isdefined therebetween. The dimensions of the vessel 18 may of course varyaccording to the object to be raised but the chamber should be largeenough so that the inner wall 20' will fit in surrounding relation overthe particular object to be raised. Although not depicted in thedrawings, the positioning of the vessel 18 over the object can beaccomplished by a remote steering means such as hydraulic steering jets.

A series of grab arms 26 are pivotally secured along both sides of thelower end of the outer wall 22. A series of double-acting,self-contained, hydraulic or electric motors 30 are pivotally secured attheir upper respective ends to the outer wall 22 and at their lower endsto one of the grab arms. The motors 30 are actuated by an electricalsignal through cable 17. As can readily be seen, an extension of themotors 30 will cause the grab arms 26 to close around the bottom of flreobject M to be raised.

The interior of the vessel is provided with a series of perforatedreinforcing ribs 32 which communicate the interior of the vessel withthe pipe string 16. A plurality of vent pipes 36 are located througheach end of the end walls 24 and extend into the chamber. The vent pipesare vertically adjustable by small electric motors 37 which receivetheir power via cable 17. The adjustable vent pipes provides a meanswhereby :a selected level of Water ballast may be maintained Within thevessel chamber.

A hydropneumatic pumping system is diagrammatically displayed in FIGURE3 and is generally represented by the numeral 38. The system 38 isprovided to inject alternate slugs of water and air into the feed pipe.The system includes an air compressor 40 and a water pump 41 which areeach connected to the feed pipe at the T-junction 43. The air compressor40 delivers pressurized air to an accumulator 48 which maintains asupply of air at a pre determined pressure. The outlet from theaccumulator goes to junction 43. An automatic air-operated valve 50 isdisposed between the accumulator and the feed pipe. The outlet from theWater pump 41 goes to the junction 43 of the feed pipe via a one-waycheck valve 52. A water bypass line 54 is provided intermediate thecheck valve 52 and the water pump and includes an air-operated valve50'. Both air-operated valves 50, 50" are controlled by a pressureregulator 56 via the lines 58 and 58.

The regulator '56 controls the air-to-water ratio delivered to the feedpipe 42 by monitoring the back pres sure in the feed pipe via the line59. When the back pressure reaches a certain preselected value, theregulator closes the valves 50, 50 thus stopping the flow of air fromentering the feed pipe and simultaneously causing an injection of waterthrough valve 52. As the weight of the water on top of the previous slugof air in the feed pipe increases the back pressure will diminish and,when this back pressure reaches a certain preselected lower value, theregulator automatically opens valves 50, 50'. Water prevented fromentering the feed pipe is discharged overboard through line 54. Whenvalve 50 is opened, another air injection on top of the previouslydelivered Water slug enters the feed pipe 42. The range set on theregulator 56 between starting and stopping water injection controls thelength of the water slugs needed to overbalance the hydrostatic head andcarry the air slugs to ever-increasing depths.

Because of the sequential operation of the valves, the pumping systemwill inject a successive series of air slugs 44 and water slugs 46 intothe pipe. The operation of this two-phase fluid fiow will result incontinuing compression of the air slugs as it is forced downwardlythrough the pipe string. In other words, the pressure head of the columnof air and water above each lower air slug will increase as the pumpsystem 38 continues to operate. Upon reaching the chamber 18, the waterslugs will fall by gravity to the bottom of chamber 22 and the excessabove the vent pipes 36 will be discharged to the sea. The air slugswill remain in the chamber to further pressurize it.

The vent pipes 36 have a further purpose. Since the pipes protrude abovethe inner surface of the end walls a water ballast sufficient tomaintain the vessel negatively buoyant can be retained in the vessel.Thus, there is no concern for the chamber rising to the surfaceuncontrolled on its own.

In operation, the chamber 18 is water filled until it is negativelybuoyant so as to facilitate its lowering. The vents 36 are raised to aselected level to insure the negative buoyancy. After the chamber hasbeen lowered to a position over the sunken object, the motors 30 areactuated to move the grab arms 26' to their engaging position. If duringthe lowering operation pipe 14 cannot support the dead weight of thechamber, air slugs can be inserted to reduce the negative buoyancy.Depending on the weight of the object to be retrieved, the verticalheight of the vent pipes can be adjusted in order to provide the systemwith a correct lifting buoyancy. The pipe string 14 is then raisedthrough the tower 12. As the retrieved object is raised an increase inthe pressure differential occurs. The air within the container willexhaust through pipes 36 to thus maintain a fixed buoyancy relationship.

Even though the above-described system is capable of lifting greatweights, the vessel 38 can be manufactured using unusually lightweightconstruction techniques. The reason for this is that since the airpressure in the vessel is always slightly higher than the ambient waterpressure, the structural integrity of the vessel is increased.

What has been set forth above is intended primarily as exemplary toenable those skilled in the art in the practice of the invention and atshould therefore be understood that, within the scope of the appendedclaims, the invention may be practiced in other Ways than asspecifically described.

What is new and therefore desired to be protected by Letters Patent ofthe United States is:

1. The method of raising a submerged object comprising the steps oflowering a hollowed vessel to a position adjacent said object, attachingsaid vessel to said object, communicating the interior of said vesselvia a feed pipe to a source of water and to a source of compressed airat a location above said vessel, injecting alternate slugs of water andcompressed air into said pipe means, exhausting said slugs of water fromsaid vessel and capturing said slugs of air therein until the airpressure reaches a level that suflicient water is exhausted from saidvessel to render the combined weight of said vessel and said objectbuoyant enough that they can be raised by said feed pipe.

2. The method of claim 1 wherein the amount of air and water isregulated to depend on the pressure in said pipe at said location.

3. Apparatus for raising a submerged object from relatively great depthsbelow the surface of a body of water comprising a hollow vessel, arelatively rigid feed pipe attached to and communicating the interior ofsaid vessel to a hoisting means above the water surface, attaching meansattached to said vessel to secure said vessel to said object, adjustablevent means to retain sufficient ballast in said vessel to insure itsnegative buoyancy as said vessel is lowered to a position adjacent saidobjects, and means to exhaust sufficient of said ballast from saidvessel to render said vessel positively buoyant to thereby reduce thecombined weight of said object and said vessel when secured together bysaid attaching means.

4. Apparatus for raising a submerged object from relatively great depthsbelow the surface of a body of water comprising a hollow vessel, a feedpipe attached to and communicating the interior of said vessel to alocation above the water surface, attaching means to secure said vesselto said object, first means to retain sufiicient ballast in said vesselto insure its negative buoyancy as said vessel is lowered to a positionadjacent said object, and second means to exhaust sufi'lcient of saidballast from said vessel to render said vessel positively buoyant tothereby reduce the combined weight of said object and said vessel whensecured together by said attaching means, said second means comprisingan air compressor and a source of water, a first conduit communicatingsaid air compressor to said feed pipe and a second conduit communicatingsaid water source to said feed pipe, and regulator means for alternatinginjecting amounts of compressed air and water into said feed pipe.

5. The invention described in claim 4 wherein said regulator meansincludes a sensing conduit in communication with said feed pipe, a firstvalving means between said compressor and said feed pipe and secondvalving means causing water to enter said feed pipe when said firstvalving means obstructs the flow of air between said compressor and saidfeed pipe.

6. The invention described in claim 5 wherein said regulator meansincludes further means to vary the amount of water delivered to saidfeed pipe in relation to the amount of air delivered thereto.

7. A salvage system for raising a submerged object comprising a shipdisposed over said object, a feed pipe de pending downwardly from saidship to the vicinity of said object, derrick means on said ship forraising and lowering said feed pipe, a hollow vessel secured to thelower end of said feed pipe, a vent stern communicating the interior ofsaid vessel to the surrounding water, clamping means affixed to saidchamber for engaging said sunken object; pumping means on said ship forpumping successive slugs or air and water into said vessel through saidpipe string, means to trap said air in said vessel, said pumping meansincluding a regulator means for adjusting the amount of water relativeto the amount of air injected into said pipe such that the columnarWeight of the water and air in said feed pipe in addition to the airpressure output of said pumping means produces a combined pressuregreater than the pressure of the water at the level of said object.

8. Apparatus for raising a submerged object from relatively great depthsbelow the surface of a body of water comprising a hollow vessel, saidhollow vessel having a concave inner surface, a feed pipe attached toand communicating the interior of said vessel to a location above thewater surface, attaching means to secure said vessel to said object,said attaching means comprising grappling members attached to saidvessel having a first position over said inner surface and a secondretracted position, first means to retain sufficient ballast in saidvessel to insure its negative buoyancy as said vessel is lowered to aposition adjacent said object, and second means to ex haust suflicientof said ballast from said vessel to render said vessel positivelybuoyant to thereby reduce the combined weight of said object and saidvessel when secured together by said attaching means.

9. Apparatus for raising a submerged object from relatively great depthsbelow the surface of a body of water comprising a hollow vessel having abottom surface, a feed pipe attache-d to and communicating the interiorof said vessel to a location above the water surface, attaching means tosecure said vessel to said object, first means to retain sufficientballast in said vessel to insure its negative buoyancy as said vessel islowered to a position adjacent 10 References Cited UNITED STATES PATENTS1,495,529 5/1924 Reno 114-52 3,339,513 9/1967 Cloutier 114-50 FOREIGNPATENTS 622,900 5/ 1949 Great Britain.

face and the upper ends of said vent pipes, and second 15 ANDREW H.FARRELL, Primary Examiner

